Remove qiskit.extensions

docs/apidoc/index.rst

@@ -18,7 +18,6 @@ API Reference
    converters
    assembler
    dagcircuit
-   extensions
    passmanager
    providers_basicaer
    providers

qiskit/circuit/library/data_preparation/state_preparation.py

@@ -18,7 +18,7 @@
 
 from qiskit.exceptions import QiskitError
 from qiskit.circuit.quantumcircuit import QuantumCircuit
-from qiskit.circuit.quantumregister import QuantumRegister, Qubit
+from qiskit.circuit.quantumregister import QuantumRegister
 from qiskit.circuit.gate import Gate
 from qiskit.circuit.library.standard_gates.x import CXGate, XGate
 from qiskit.circuit.library.standard_gates.h import HGate
@@ -413,114 +413,3 @@ def _multiplex(self, target_gate, list_of_angles, last_cnot=True):
             circuit.append(CXGate(), [msb, lsb])
 
         return circuit
-
-
-def prepare_state(self, state, qubits=None, label=None, normalize=False):
-    r"""Prepare qubits in a specific state.
-
-    This class implements a state preparing unitary. Unlike
-    :class:`qiskit.extensions.Initialize` it does not reset the qubits first.
-
-    Args:
-        state (str or list or int or Statevector):
-            * Statevector: Statevector to initialize to.
-            * str: labels of basis states of the Pauli eigenstates Z, X, Y. See
-              :meth:`.Statevector.from_label`. Notice the order of the labels is reversed with respect
-              to the qubit index to be applied to. Example label '01' initializes the qubit zero to
-              :math:`|1\rangle` and the qubit one to :math:`|0\rangle`.
-            * list: vector of complex amplitudes to initialize to.
-            * int: an integer that is used as a bitmap indicating which qubits to initialize
-              to :math:`|1\rangle`. Example: setting params to 5 would initialize qubit 0 and qubit 2
-              to :math:`|1\rangle` and qubit 1 to :math:`|0\rangle`.
-
-        qubits (QuantumRegister or Qubit or int):
-            * QuantumRegister: A list of qubits to be initialized [Default: None].
-            * Qubit: Single qubit to be initialized [Default: None].
-            * int: Index of qubit to be initialized [Default: None].
-            * list: Indexes of qubits to be initialized [Default: None].
-        label (str): An optional label for the gate
-        normalize (bool): Whether to normalize an input array to a unit vector.
-
-    Returns:
-        qiskit.circuit.Instruction: a handle to the instruction that was just initialized
-
-    Examples:
-        Prepare a qubit in the state :math:`(|0\rangle - |1\rangle) / \sqrt{2}`.
-
-        .. code-block::
-
-           import numpy as np
-           from qiskit import QuantumCircuit
-
-           circuit = QuantumCircuit(1)
-           circuit.prepare_state([1/np.sqrt(2), -1/np.sqrt(2)], 0)
-           circuit.draw()
-
-        output:
-
-        .. parsed-literal::
-
-                 ┌─────────────────────────────────────┐
-            q_0: ┤ State Preparation(0.70711,-0.70711) ├
-                 └─────────────────────────────────────┘
-
-
-        Prepare from a string two qubits in the state :math:`|10\rangle`.
-        The order of the labels is reversed with respect to qubit index.
-        More information about labels for basis states are in
-        :meth:`.Statevector.from_label`.
-
-        .. code-block::
-
-            import numpy as np
-            from qiskit import QuantumCircuit
-
-            circuit = QuantumCircuit(2)
-            circuit.prepare_state('01', circuit.qubits)
-            circuit.draw()
-
-        output:
-
-        .. parsed-literal::
-
-                 ┌─────────────────────────┐
-            q_0: ┤0                        ├
-                 │  State Preparation(0,1) │
-            q_1: ┤1                        ├
-                 └─────────────────────────┘
-
-
-        Initialize two qubits from an array of complex amplitudes
-        .. code-block::
-
-            import numpy as np
-            from qiskit import QuantumCircuit
-
-            circuit = QuantumCircuit(2)
-            circuit.prepare_state([0, 1/np.sqrt(2), -1.j/np.sqrt(2), 0], circuit.qubits)
-            circuit.draw()
-
-        output:
-
-        .. parsed-literal::
-
-                 ┌───────────────────────────────────────────┐
-            q_0: ┤0                                          ├
-                 │  State Preparation(0,0.70711,-0.70711j,0) │
-            q_1: ┤1                                          ├
-                 └───────────────────────────────────────────┘
-    """
-
-    if qubits is None:
-        qubits = self.qubits
-    elif isinstance(qubits, (int, np.integer, slice, Qubit)):
-        qubits = [qubits]
-
-    num_qubits = len(qubits) if isinstance(state, int) else None
-
-    return self.append(
-        StatePreparation(state, num_qubits, label=label, normalize=normalize), qubits
-    )
-
-
-QuantumCircuit.prepare_state = prepare_state